# How is the qubit sent from Alice to Bob in superdense coding?

I'm reading studying a book: Principles of Quantum Computation and Information Volume I: Basic Concepts by Giuliano Benenti ... And I have a question on page 216 about Dense coding. In summary, we have:

1. A source S generates an EPR pair shared by Alice and Bob. The EPR pair is prepared, for instance, in the state $$|Φ^+⟩ = \frac{1}{\sqrt2}(|00⟩ + |11⟩)$$ (OK)

2. There are four possible values of the two classical bits that Alice wishes to send to Bob: 00, 01, 10 and 11. They determine the unitary operation U that Alice performs on her half of the EPR pair: $$U = \{I, σ_x, σ_z, iσ_y\}$$. (OK)

3. Alice sends her half of the EPR pair to Bob. (??)

The entangled pair was not shared between Alice and Bob. Does one qubit stay with Alice and the other with Bob? So what does the author mean by sending the qubit to Bob? How is this done? That detail stopped me.

My context is quantum computing. What comes to mind in entanglement are two fixed and separate qubits, like two spins-1/2. Can someone help me understand please? Thanks.